1. Technical Field of the Invention
The present invention relates to a socket for a semiconductor device, and more specifically to a socket for use in measuring electrical characteristics of a semiconductor device.
2. Description of the Prior Art
A conventional socket which has been used for electrically testing a semiconductor device includes a body 10 and a cover 20 as shown in FIGS. 1 and 2.
With reference to FIG. 1, a conventional socket with a body 10 and a cover 20 is shown in an open position. The body 10 is provided with a guide 15 into which the leads of the semiconductor device 30 are placed. The guide 15 is provided with a plurality of guiding grooves 17 disposed at intervals corresponding to the lead intervals of the device. The cover 20 is pivotally connected to a projecting portion 12 of the body 10. A surface of the cover 20 facing the body 10 supports a push projecting portion 21 in a position aligned with the guide 15.
FIG. 2 shows a conventional socket in a closed position and holding a semiconductor device 30. Individual metal pads 11 are disposed at the bottom of each of the grooves 17. These metal pads 11 occur at the same intervals as the intervals of the leads 31 of the semiconductor device 30, so that the leads 31 and the metal pads 11 correspond when the semiconductor device 31 is coupled to the guide 15. Further, one of a plurality of out-leads 14 is connected to each of the metal pads 11 so as to connect them to the outside. This enables the semiconductor device to communicate with external devices through the combination of the socket's metal pads and out-leads.
The conventional socket uses a locking mechanism for holding the body 10 and cover 20 together. As discussed above, the cover 20 is rotatably mounted to a projecting portion 12, formed on one side of the body 10. An engaging step 13 is formed on another side of the body 10. The cover 20 pivots within a predetermined angular range with respect to the projecting portion 12 for allowing the socket to rotate into a closed position by engaging the locking portion 16 of the cover with the engaging step 16 of the body 10. Similarly, the socket may be opened by moving the locking portion 16 beyond the reach of the engaging step 16 for allowing the cover 20 to rotate to an open position.
The push projecting portion 21 elastically pushes the semiconductor device 30 toward the body 10 as the cover 10 is closed. The push projecting portion 21 is made of a pliable material that is capable of compression as it engages the semiconductor device 30. As the cover 20 is closed, the push projecting portion 21 contacts the semiconductor device 30 and compresses to maintain a constant force on the semiconductor device 30 to ensure that the leads 31 reach and remain in contact with the metal pads 11 for allowing the device to communicate through the out-leads 14 to outside devices.
Proper contact between the leads 31 and the metal pads 11 must be maintained for the socket to work reliably in testing and measuring the semiconductor device. When low voltage signals or high frequency signals are supplied to the semiconductor device, the electrical signals may be distorted or damped if the leads do not remain in contact with the metal pads. The result being that any measurements of the characteristics of the device 30 become inaccurate.
Unfortunately, a conventional socket has several inherent problems that prevent consistent contact between the semiconductor device and the socket. With the arrangement shown in FIGS. 1 and 2, the contacting state of the leads 31 with the metal pads 11 varies with the thickness of the semiconductor device 30 and with the thickness of the push projecting portion 21 of the cover 20. Thus, conventional sockets can only be used with semiconductor devices within a narrow range of thicknesses. For example, if the device width is smaller than the range of device width determined by the elasticity of the push projection portion, the push projection portion will not provide sufficient force on the device to ensure proper contact between the leads and the metal pads. Further, the thickness of the push projecting portion 21 may gradually decrease as the elasticity of the material comprising the push projecting position 21 decreases. This effectively narrows the range of device thicknesses that the socket can accommodate and still function reliably.